Does someone know, how to create an application, witch expands the
environment path from windows?

From the history something like path = %path%;xyz;

The windowsenvironment is set normaly in

HKLM/SYSTEM/CurrentControlSet/Session Manager/Environment
Path = ....

If i try to use the %path% variable, it clears everything and expand only
the searchdrive from Network.

I need no fixed entry, cause other programs need also to expand the
pathvariable, but not every program is associated to each user.